1. Field of the Invention
The invention relates to an unvulcanized rubber mixture, in particular for tire treads, that can be cross linked with sulfur.
2. Discussion of Background
Since the road handling of a tire depends to a great extent on the unvulcanized rubber composition of the tread, particularly high demands are put on the composition of the tread mixture. It could, for example, be determined that by varying the fillers, the characteristics of the tire such as wear, road drag, and wet traction could be influenced. But the effectiveness of these fillers depends upon which other components (further additives such as catalysts, softeners, anti-aging agents) are mixed into the unvulcanized rubber mixture for treads. For example, tread mixtures are known that contain an active filler that consists for the most part of silicic acid. These tread mixtures containing silicic acid give the tire low road drag and good wet traction. The unvulcanized rubber components of these silicic-acid-containing mixtures are vulcanized by sulfur and a suitable cross-linking system. An example of a suitable cross-linking system is vulcanization catalyst benzothiazyl-2-cyclohexylsulfenamide (CBS) and diphenylguanidine (DPG). But it has been observed that unvulcanized rubber mixtures of this kind give the vulcanized tread a low tensile strength and a low ultimate elongation so that these tires exhibit only limited wear resistance.